JP3100317B2 - Method of manufacturing extensible nonwoven fabric - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to
The present invention relates to a method for producing an easily extensible nonwoven fabric having 0% or more extensibility. Such an easily extensible nonwoven fabric is advantageously used in particular for forming a sheet material having a good touch, which is most suitable for a material of a product such as a garment or a sanitary article by being combined with a sheet-like elastic body.

[0002]

2. Description of the Related Art In various products used in contact with the skin, such as skin clothing and hygiene articles, a non-woven fabric is generally used as a stretchable film or a net-like elastic body because of the problem of texture. .

[0003] Various methods have conventionally been applied to the production of a composite elastic body composed of a nonwoven fabric and an elastic body, but none of the above-mentioned satisfactory materials can be obtained.

Accordingly, the present inventors have proposed a method for producing a nonwoven fabric which has extensibility in the direction in which the elastic body extends and has a certain breaking strength (Japanese Patent Laid-Open No. 5-245).
No. 961).

[0005]

However, according to the conventional method as described above, in order to obtain a good touch, in order to produce a material which is optimal as a material for a product such as skin clothing or sanitary goods, it is necessary to easily extend the material. As the nonwoven fabric, a spunlace nonwoven fabric by a hydroentanglement method must be used. This spunlaced nonwoven has the disadvantage of being relatively more expensive than other forms of nonwovens, such as spunbonded nonwovens and thermal bonded nonwovens.

[0006] On the other hand, spunbond and thermal bond nonwoven fabrics are inexpensive, but have extremely low extensibility compared to spunlace nonwoven fabrics. This is why the development of a method capable of producing an extensible nonwoven fabric is required.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in response to the above-mentioned demands, and comprises a skeleton component (B) having a relatively heat-stable skeleton component (B) and a thermoplastic component (A). composite nonwoven fabric composed of fibrous material consisting of at plasticizing temperature or more Ekinetsu thermoplastic bonding component constituting the nonwoven fabric (a), moreover width under heating at stable temperature region framework component (B) In the direction of widening more than 1.2 times
It is characterized in that a stretching process is performed in a direction perpendicular to the direction . The easily extensible nonwoven fabric obtained by this method has an extensibility of 100% or more in one direction and is also excellent in feel such as touch, and the elastic composite obtained by combining this nonwoven fabric is Ideal as an elastic material for products such as skin clothing and hygiene products.

In the present invention, in order to provide a structure having easy extensibility while maintaining the shape and properties of the nonwoven fabric, it is necessary to reorient the constituent fibers while maintaining the longitudinal-lateral bond. In order to satisfy this condition, in the present invention, in the composite nonwoven fabric comprising the bonding component (A) and the skeleton component (B) as described above, the bonding component (A) is plasticized by heating, and its fluidity is increased. Is used to reorient while shifting the constituent fibers by a drawing operation.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a composite nonwoven fabric as a starting material, a bonding component (A) which is easily thermoplastic and a skeleton component (B) which is relatively thermally stable with respect to the bonding component (A).
Will be described. Both the bonding component (A) and the skeleton component (B) have a filamentous, stable, or fibril-like fibrous form. An example of a combination of the bonding component (A) and the skeleton component (B) is as follows. For example, there is something like the table below.

[0010]

[Table 1] In the above-mentioned combination, at least the skeleton component (B) preferably has a staple shape, more preferably a continuous filament-like fiber shape in which the orientation of the fiber easily occurs by drawing.

Examples of the composite state include a single-layer composite nonwoven fabric having two components, component (A) and component (B), and a nonwoven web composed of the bonding component (A) and a skeleton component (B). ) May be overlaid in multiple layers.

An example of the single layer is a filament non-woven fabric made of a conjugate fiber of PE (polyethylene) / PET (polyester), for example, a non-woven fabric such as Spunbond (Elves) manufactured by Unitika.

Examples of the multi-layered structure include an example in which a hot-melt meltblown web is superimposed on a PET spunbond as a center, or an acetate tow is opened, and the fibrils are formed on the upper and lower cores. A typical example is a multi-layer nonwoven fabric obtained by laminating PP (polypropylene) fibers (referred to as burst fiber). Generally, it is preferable that the skeleton component (B) is distributed in the center and the bonding component (A) is distributed in the surface layer.

Thus, even if the surface portion is easily softened and heated by heating, it is possible to maintain a structure in which the basic physical properties do not deteriorate or deteriorate.

[0015] Examples of easily extensible nonwoven fabrics include tow-spread nonwoven fabrics close to parallel filament bundles, foamed nets obtained by a melt extrusion method, and unbonded parallel card webs. Although it has easy extensibility, on the other hand, the lateral strength is extremely weak, which is not suitable for the purpose of the present invention. Also, by stretching in a heating atmosphere, a normal spunbond which is a filamentous nonwoven fabric is oriented in the longitudinal direction, and a nonwoven fabric which is easily extensible in the transverse direction can be obtained. It is not suitable for the purpose of the present invention.

In order to form a structure having excellent extensibility while maintaining sufficient strength for the application as the object of the present invention, it is necessary that the constituent fibers be entangled with each other. It is necessary to be. That is, the orientation state of the web suitable for the present invention is a so-called spunbond or a tow-shaped filament bundle in which the web is formed in a state where the filaments are piled up in a loop shape, and a random bundle obtained by widening and overlapping. Web, etc.,
These have the property of being easily reoriented by hot stretching.

From such a viewpoint, a nonwoven fabric formed by heat-bonding a parallel dry web of short fibers already in an oriented state is less preferred. On the other hand, nonwoven fabrics in which the web is joined vertically / horizontally with a cross wrapper,
The vertical / horizontal confounding is too strong and not very desirable.

In order to obtain a web having excellent lateral extensibility by stretching and re-orienting a web having the above-mentioned properties under heating, stretching conditions, ie, temperature conditions applied to the web during stretching, are required. It is important to appropriately select conditions such as the type of heating medium used for heating.

[Temperature condition] Of the bonding component (A) and the skeleton component (B) constituting the composite nonwoven fabric, only the thermoplastic thermoplastic bonding component (A) is plasticized, and the skeleton component (B) is stable. It is desirable to perform stretching in a certain temperature range, and generally a temperature range of about 90 ° C. to 160 ° C. is appropriate.
For example, in the case of a combination of PE / PET, about 100 ° C. to 120 ° C. is desirable.

[Heating Medium] The most suitable heating medium is a fluid containing water, specifically steam and hot water. Stretching performed in such a heating medium does not cause bonding of the constituent fibers of the web to each other, and gives an easily extensible nonwoven fabric having a soft finish. The reduction in denier of the constituent fibers due to drawing also contributes to the softening.

It is desirable to use steam or hot water in a combination of hot water and hot air, or steam and hot air, rather than using it alone. Particularly, when stretching is performed in multiple stages, a plurality of heating media are combined. It is desirable to use them together.

It is to be noted that a general heating roll or dry hot air as a heating means is not preferable because there is a risk that the constituent fibers of the web are thermally fused.

When stretching is performed under heating, widening is performed as a preliminary treatment, and then stretching is performed, so that an easily extensible nonwoven fabric of good quality can be obtained more easily. In this case, the widening does not need to be so large.
About 0% to 150% is sufficient. For this widening, an expander roll or a greed gear can be used. Performing such widening in hot air at 70 ° C. to 80 ° C. and then stretching in saturated steam is a recommended effective method.

FIG. 1 is a system diagram showing an example of the steps of the method of the present invention. In FIG. 1, the raw fabric made of the composite nonwoven fabric was first widened under steam heating (step S).
1) Thereafter, the film is stretched in a direction substantially perpendicular to the widening direction under steam heating (step S2), then dried (step S3), and finally wound up in a roll shape (step S4). Depending on conditions such as the properties of the raw material to be used, the widening step (step S1) may be omitted and the direct stretching step (step S2) may be performed without widening.

FIG. 2 is a longitudinal sectional view showing a structural example of a composite nonwoven fabric suitable for use as a raw material in the method of the present invention. The extensible nonwoven fabric of FIG. 2 has a PET spunbond web layer 1 constituting a centrally located skeletal component (B).
Has a configuration of a multi-layer nonwoven fabric in which a PE melt blown web layer 2 constituting the bonding component (A) is laminated on both upper and lower surfaces. Alternatively, as shown in FIG. 3, the bonding component (A) is provided on one surface of the PET web layer 3 constituting the skeleton component (B).
Can be adopted in which two sets of the laminated PP burst fiber web layers 4 constituting the above are laminated so that the skeleton component (B) layers 3 face each other.

In order for the composite nonwoven fabric used in the method of the present invention to withstand the widening and strong stretching in the process of manufacturing an easily extensible nonwoven fabric and to perform a desired reorientation, the layers constituting the composite nonwoven fabric are mutually interlinked. It is desirable to have an appropriate bonding state.

Even if each non-woven fabric is bonded to the other non-woven fabric over its entire surface, if the degree of bonding is appropriate, that is, if it is bonded to such an extent that it has a certain degree of freedom in orientation of the fiber, such a non-woven fabric can be used. Complex nonwoven fabrics can also be used. However, in order to increase the overall drawing uniformity, those connected at a number of small connection points are advantageous. Also in this case, if the fusion at each bonding point is too strong, other than the bonding between the bonding component (A) and the bonding component (A) and between the bonding component (A) and the skeleton component (B). In addition, since the skeleton component (B) is strongly bonded to each other, the skeleton component (B) becomes brittle at this portion, and the stretchability may be lost.

In order to avoid such inconvenience, it is effective to adopt a two-phase coupling structure in which two kinds of coupling points P and Q having different coupling degrees are distributed at appropriate intervals as shown in FIG. 4, for example. It is one of the means. At the bonding point Q, the temperature and pressure during fusion are suppressed to limit the bonding between the bonding component (A) and the bonding component (A) and the bonding between the bonding component (A) and the skeleton component (B). At the bonding point P, a temperature at which the bonding between the skeleton component (B) and the skeleton component (B) also occurs;
The connection is made under pressure conditions.

[0029]

【Example】

(Example 1) Polyester core of preparation framework component of the raw nonwoven fabric (B), the polyethylene as the bonding component (A) consisting of conjugate fibers as a sheath, the width 1 m, spunbonded nonwoven fabric having a basis weight of 25 g / m ² (Made by Unitika, trade name "Elves") was prepared. This non-woven fabric, after forming the web by the spun bond method,
Spot-shaped bonding points are distributed at a predetermined density.
Expressing the distribution ratio of spot junctions as the total area ratio,
Its physical properties were as follows. The plasticization temperature of PET as the skeleton component (B) is about 90 ° C, and the stable temperature range is about 100 to 130 ° C.

・ Tensile strength Length: 12.5 kgf / 5 cm Width: 4.5 kgf / 5 cm Length / width ratio: 2.8 ・ Elongation at break Length: 60% Width: 60% Width / length ratio: 1 The above spunbond nonwoven fabric At a speed of about 10 m / min into a pressurized steam processor equipped with a clip tenter, and 105 ° C. while widening about 1.5 times in the processor.
Heated to ~ 115 [deg.] C. The nonwoven fabric exiting the processing machine was dried at room temperature and then wound up. Some water remained in the widened nonwoven fabric. The basis weight was about 18 g / m ² . Next,
This widened nonwoven fabric is stretched about 2.2 times in the machine direction (MD) through a perforated cylinder equipped with a steam generator,
After drying with warm air, winding was performed. The basis weight is about 22g / m
^{Was 2} .

The obtained easily extensible nonwoven fabric had mesh-shaped openings, was soft, and extremely rich in lateral extensibility.

The physical properties were as follows.

・ Tensile strength Length: 8.7 kgf / 5 cm Width: 1.5 kgf / 5 cm Length / width ratio: 5.8 ・ Elongation at break Length: 30% Width: 280% Width / length ratio: 9.3 From this, it can be seen that the elongation in the transverse direction (the direction perpendicular to the stretching) is greatly increased as compared with the raw material nonwoven fabric.

(Comparative Example 1) The same spunbonded nonwoven fabric as used in Example 1 was cut in an attempt to stretch twice in a state of being heated in dry hot air at 130 ° C.

When a sample obtained by stretching 1.5 times under the same temperature conditions was examined, the elongation at break was 60% to 10%.
Although the extensibility was improved by increasing to 0%, the surface was rough and was not a favorable texture. When pressed with a roller in a heated state, the surface became smooth, but the extensibility was greatly reduced.

(Comparative Example 2) When a polypropylene nonwoven fabric with a basis weight of 25 g / m ² was stretched to about 2.0 in hot air of 130 ° C under hot air at 130 ° C, it became tow-like, and although it had extensibility, it had fibers. Were scattered, had poor morphology, and were not suitable for use.

Example 2 An unbonded PET spunbond web having a basis weight of about 10 g / m ² was prepared as the skeletal component (B). After superimposed meltblown web composed mainly of ² PE, subjected lightly meshed Bonding was prepared a multi-layer nonwoven fabric of about 24 g / m ² having the configuration shown in FIG. This multilayer nonwoven fabric was stretched about 1.8 times while being heated in a continuous process at about 120 ° C. by a roll in a multistage stretching apparatus equipped with infrared heating lamps at the top and bottom.

As a result, an easily extensible nonwoven fabric which was soft and had excellent lateral extensibility was obtained.

The physical properties were as follows.

Tensile strength length: 9.5 kgf / 5 cm width: 0.85 kgf / 5 cm length / width ratio: 11.0 ・ breaking elongation length: 30% width: 180% width / length ratio: 6 (Example 3) ) A nonwoven fabric (trade name: Unicell, manufactured by Teijin Co., Ltd.) was prepared by laminating a burst fiber web of polypropylene on the upper and lower surfaces of a widened polyester tow web having a basis weight of 30 g / m ² . Its structure was as shown in FIG. 3, and its physical properties were as follows.

-Tensile strength length: 6.3 kgf / 5 cm width: 6.5 kgf / 5 cm length / width ratio: 1.0-elongation at break length: 80% width: 60% width / length ratio: 0.8 Heat treatment conditions The 1 m wide nonwoven fabric is passed through a normal pressure steam at a speed of about 20 m / min, is stretched stepwise through four rolls, stretched about 2.0 times, and dried with hot air at about 70 ° C. Winding was performed. A soft nonwoven fabric with large lateral extensibility was obtained, albeit with some swelling. The basis weight was about 20 g / m ² .

Easily extensible nonwoven fabric The obtained nonwoven fabric had a lace-like appearance and was extremely excellent in lateral extensibility.

The physical properties were as follows.

・ Tensile strength Length: 4.0 kgf / 5 cm Width: 1.1 kgf / 5 cm Length / width ratio: 3.6 ・ Elongation at break Length: 42% Width: 258% Width / length ratio: 6.1 Stretching It can be seen that the lateral elongation is significantly increased as compared to the previous raw nonwoven fabric.

Example 4 The nonwoven fabric of Example 2 was replaced with SEB
The upper and lower layers are sandwiched around an elastomer film 40 μ (manufactured by Klopei U.S.A.) containing S as a main component, and are stacked on a 40 mesh plastic net.
When a pair of chrome-plated flat rolls heated to 0 ° C. were passed at a pressure of ² kg / cm ² , a point-joined composite elastic body was obtained.

The elastic body was excellent in stretch elasticity, and had a first break point based on breaking of the nonwoven fabric and a second break point based on breaking of the elastic body.

The various properties are as follows:-Residual strain during 3-cycle hysteresis test at 150% elongation: 15%-First stage elongation at break: 185%-Second stage elongation at break: 385% (implementation Example 5) The easily extensible nonwoven fabric obtained in Example 1 was overlaid on both the upper and lower surfaces of a net-like SEBS-based elastic body (manufactured by Mitsui Petrochemical, trade name "Netron") with a basis weight of 110 g / cm ² , and the whole was Thermal bonding was performed at the spot.

The easily extensible nonwoven fabric thus obtained was rich in stretch elasticity, and had a first break point based on the breaking of the nonwoven fabric and a second break point due to the elastic breakage.

The elongation at break of the first stage was 320%, and the elongation at break of the second stage was 440%.

[0050]

According to the present invention as described above,
Using an inexpensive material, it is extremely easy to manufacture an easily extensible nonwoven fabric having optimal flexibility and elasticity as a material used in contact with the skin, such as skin clothing and hygiene products. It is possible.

Further, the easily extensible nonwoven fabric produced by the method of the present invention is a sheet material having a good texture, which is optimal for materials of products such as skin clothing and sanitary goods.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of the steps of the method of the present invention.

FIG. 2 is a longitudinal sectional view showing a configuration example of a composite nonwoven fabric suitable for use as a raw material in the method of the present invention.

FIG. 3 is a longitudinal sectional view showing another configuration example of a composite nonwoven fabric suitable for use as a raw material in the method of the present invention.

FIG. 4 is a plan view showing the bonding affection of a composite nonwoven fabric suitable for use as a substrate in the method of the present invention.

[Explanation of symbols]

 Reference Signs List 1 PET spunbond web layer 2 PE melt blown web layer 3 PET web layer 4 PP burst fiber web layer P, Q bonding point

Claims (8)

(57) [Claims] 1. A composite comprising a fibrous material comprising an easily thermoplastic joining component (A) and a skeletal component (B) which is relatively thermally stable with respect to the joining component (A). The nonwoven fabric is expanded at least 1.2 times in the width direction in a state where the nonwoven fabric is heated to a temperature within the stable temperature range of the skeleton component (B) at a temperature equal to or higher than the plasticizing temperature of the easily thermoplastic bonding component (A) , Then expand
A method for producing an easily extensible nonwoven fabric having an extensibility of 100% or more in one direction orthogonal to the stretching direction, wherein the stretching is performed in a direction substantially orthogonal to the width direction . 2. The method according to claim 1, wherein the composite nonwoven fabric is mainly composed of a filamentous nonwoven fabric having a high randomness and a longitudinal / transverse strength ratio of 3.0 or less. 3. The non-woven fabric according to claim 1, wherein said composite non-woven fabric is mainly composed of a conjugate fiber having a sheath of polyethylene and a core of polyester and a ratio of polyethylene of 40% or more. The method described in. 4. The composite nonwoven fabric according to claim 1, wherein the unbonded spunbond is a core, and a melt blown web made of a thermoplastic resin is laminated on an upper surface and / or a lower surface. The described method. 5. The composite nonwoven fabric according to claim 1, wherein unbonded filaments are spread and widened, and a fibril-like thermoplastic resin is laminated on an upper surface and / or a lower surface thereof. The method described in the section. Wherein said stretching treatment, using steam as the heating medium, the method according to any one of claims 1 to 5 carried out in the steam atmosphere. 7. The method according to claim 1 , wherein the stretching is performed in hot water as a heating medium. 8. A horizontal / vertical stretch when the vertical / horizontal strength ratio is 3.0 or more.
An easily extensible nonwoven fabric having a degree ratio of 5.0 or more and obtained by the method according to any one of claims 1 to 6 .